Gripping elements for carbon anode stacker

ABSTRACT

Gripping elements are mounted on an anode stacker for grasping carbon anode blocks and releasing the blocks at a desired location. Each of the gripping elements has a drive means for operating the gripping element. The drive means includes a toggle joint having two pivotally interconnected links in which one of the links has an adjustable length with a compression spring biasing the link to the maximum length. A hydraulic cylinder is connected to the knee of the toggle joint for straightening and bending the knee to operate the gripping element.

United States Patent [72] Inventor Donald H. Shadle Spokane, Wash. [21] Appl. No. 851,814 [22] Filed Aug. 21, 1969 [45] Patented Oct. 19, 1971 [73] Assignee General Machinery Company Spokane, Wash.

[54] GRIPPING ELEMENTS FOR CARBON ANODE STACKER 4 Claims, 7 Drawing Figs.

[52] 11.8. CI 294/104, 294/88, 74/106, 74/520 [51] Int. Cl B66c 1/00 [50] Field of Search 294/67, 104,103, 88; 74/106, 520

[56] References Cited UNITED STATES PATENTS 709,167 9/1902 Martin 74/106 1,542,341 6/1925 Deckert 74/520 2,369,362 2/1945 Marziani 74/106 2,457,646 12/1948 Dacfer 4. 294/104 2,542,320 2/1951 Forse......v 74/106 2,782,067 2/1957 Bonte 294/104 2,789,813 4/1957 Runkle 74/520 2,995,043 8/1961 Lusk 74/106 3,175,698 3/1965 Dassler 74/106 FOREIGN PATENTS 1,015,022 9/1957 Germany 212/17 Primary Examinerl'larvey C Hornsby Attorney-Wells & St. John ABSTRACT: Gripping elements are mounted on an anode stacker for grasping carbon anode blocks and releasing the blocks at a desired location. Each of the gripping elements has a drive means for operating the gripping element The drive means includes a toggle joint having two pivotally interconnected links in which one of the links has an adjustable length with a compression spring biasing the link to the maximum length. A hydraulic cylinder is connected to the knee of the toggle joint for straightening and bending the knee to operate the gripping element.

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INVENTOR. Donald H. Shad I:

GRIPPING ELEMENTS FOR CARBON ANODE STACKER BACKGROUND OF THE INVENTION This invention relates to anode stacking equipment and more particularly to gripping elements on the stacking equipment for gripping carbon anodes as the anodes are being picked up and transferred to a desired location and stacked.

In the electrolytic process for the production of aluminum from bauxite, carbon anodes are utilized in the electrical circuit. The oxygen liberated in the process reacts with the carbon anode to form carbon monoxide and dioxide. For each pound of aluminum formed during the process, approximately 6/10 of a pound of carbon is expended. This means that a great number of carbon anodes are required in any substantial production of aluminum.

Each of the carbon anodes are quite heavy and bulky yet quite fragile. The anodes are generally molded and baked into blocks. Two common sizes are 38 inches X 20 inches X 22 inches and 41 inches X 31 inches X 24 inches. Each block weighs several hundred pounds. If the anodes are dropped they are easily damaged or broken. The carbon blocks are quite expensive and represent a substantial investment. Loss of one or more anodes can be costly. The handling of the blocks from the location where they are formed to a storage facility and then from the storage facility to the electric furnaces represents a difficult handling problem.

A present commercially available stacker includes a gripping element having a hydraulic actuator that is extended to grip an anode between the gripping element and a backing plate. It has been found that this arrangement has many disadvantages; one of which is that if the hydraulic pressure is lost on the stacker, the gripping elements drop the anodes. As previously mentioned, this could result in a considerable loss. A further problem represented by the present equipment is that as the hydraulic actuators become worn the effective gripping force decreases until the gripping elements become ineffective for gripping and holding the anodes.

One of the principal objects of this invention is to provide a gripping means for a carbon anode stacker that will maintain the gripping force on the anode to hold the anode to the stacker even through hydraulic pressure is lost to the stacker.

An additional object of this invention is to provide gripping elements for a carbon anode stacker that have a uniform gripping pressure on the anodes which is uneffected by the hydraulic pressure to the stacker.

A further object of this invention is to provide gripping elements on a carbon anode stacker that utilizes a novel drive means with a locking feature to maintain the gripping element in engagement with the carbon anodes even though power to the stacker may be lost.

A still further object of this invention is to provide gripping elements for an anode stacker that are inexpensive to manufacture and easy to maintain.

These and other objects and advantages of this invention will become apparent upon the reading of the following detailed description of a preferred embodiment.

BRIEF DESCRIPTION OF THE DRAWINGS A preferred embodiment of this invention is illustrated in the accompanying drawings, in which:

FIG. I is a fragmentary vertical cross-sectional view through a section of an anode stacker transversely to the longitudinal axis of the stacker showing a prior art gripping element;

FIG. 2 is a vertical cross-sectional view similar to FIG. 1 except showing an improved gripping element;

FIG. 3 is a fragmentary side view of a section of the stacker showing an end view of the gripping element shown in FIG. 2;

FIG. 4 is a top view of a section of the stacker showing the gripping elements elements shown in FIG. 2;

FIG. 5 is a cross-sectional view taken along line 55 in FIG.

FIG. 6 is a cross-sectional view taken along line 66 in FIG. 2; and

FIG. 7 is a vertical cross-sectional view showing the stacker preparing to pick up an anode.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now in detail to the drawings, there is shown in FIG. 7 an anode-stacking machine 10 for picking up carbon anodes 11 and transferring the anodes to a desired location, and stacking the anodes. The anode-stacking machine 10 has a crane 13 including parallel support rails 14 and 15 forming part of a travelling crane for transporting the anodes to the desired location. The stacking machine 10 has a pickup frame 14 suspended from the crane 13 by cables 18 which are wound on drums 17 fixed on shafts 16 on the crane for raising and lowering the frame I4 as desired.

The pickup frame 14 has parallel longitudinal channel members 21 and 22 that extend the full length of the pickup frame. Cross channels 23 are welded between the longitudinal channels 21 and 22 at spaced intervals along the full length of the channels 21 and 22. A longitudinal backing plate 24 is mounted to the underside of the cross channels 23 immediately below the longitudinal channel 22 for engaging one end of the carbon anode blocks 1 l.

A plurality of gripping elements 26 are mounted on the pickup frame 14 at evenly spaced intervals on pickup frame for engaging and pressing anode blocks 11 against the backing plate 24, with enough force to hold the blocks so they may be lifted with the pickup frame.

Each of the gripping elements 26 includes a pivot arm 27 that is pivotally mounted between two adjacent cross channels 23 (FIGS. 3 and 4) intermediate its ends on a pivot shaft 28. One end 30 of the arm 27 extends upward above the channels 23 and the other end 31 extends in a generally downward direction. A gripping plate 32 is mounted to the end 31 for gripping one end of the anode block 11. The gripping plate 32 has a bracket 33 mounted on the back thereof that is pivotally connected to the end 31 by a pin 34 so that the gripping plate is substantially self-centering for engaging the end of the carbon anode block 1 1.

FIG. 1 illustrates a prior art drive means for pivoting the arm 27 to grip the anode between the gripping plate 32 and the backing plate 24. The prior art drive means includes a hydraulic cylinder 37 mounted on a bracket 36 that is affixed to the cross channels 23. The cylinder 37 is pivotally supported on the bracket 36 at point 38. The cylinder 37 has a piston rod 40 with a clevis 41 formed on the end thereof pivotally interconnected to the arm end 30. To grip the. carbon anode 11 between the gripping plate 32 and the backing plate 24, hydraulic pressure must be applied and maintained in the cylinder 37 to extend the piston rod outward. Should the pressure in the cylinder 37 fall the gripping pressure would decrease and thereby release the carbon block. If the pickup frame 14 is in an elevated position, the released carbon block would fall to the ground and become extensively damaged. A similar result would happen if the hydraulic pressure to the cylinder 37 decreased below a prescribed level.

The object of an improved reversible drive means 43, shown in FIGS. 2-7, is to overcome these objections and provide a more satisfactory drive means.

The improved drive means 43 includes a toggle joint 44 that is pivotally interconnected between the end 30 and the bracket 36. The toggle joint 44 has two links 45 and 46 that are pivotally interconnected with one end of the link 45 pivotally connected to the end 30 of the lever arms 27 by a pivot pin 48. The outer end of the link 46 is pivotally connected to the bracket 36 by a pivot pin 50. The links 45 and 46 are pivotally interconnected to each other through a knee pin 51 defining a pivot knee of the toggle joint.

The link 45 includes two side bars 52 and 53 (FIG. 5) that are pivotally connected to the pins 48 and 51.

The link 46 is made up of two telescoping members 55 and 56. The telescoping member 55 is constructed with a central shaft having cars 58 formed on one end thereof. A transverse aperture 59 is formed in each of the ears 58 to receive the knee pin 51. An elongated transverse slot 61 is formed in the other end of the shaft 57 to receive the pin 50. The length of the slot 61 defines the limits of the variable length of the link 46. The telescoping member 56 has a tube 62 that is slidably mounted on the outside of the shaft 57 with transverse apertures 63 formed therein to receive the pin 50. A shoulder 64 is formed on the exterior of the tube 62. A complementary shoulder ring 65 is affixed to the exterior of the shaft 57 adjacent the ears 58.

The telescoping members 55 and 56 are spring biased to extend the link 46 to its maximum length as defined by the length of the slot 61. The biasing means includes a compression spring 67 that is mounted on the exterior of the shaft 57 and cylinder 62 engaging the shoulder 64 and 65. The compression spring 67 provides several advantages. One of the advantages is that it provides a spring force on the arm 27 of a substantially constant magnitude which is extremely reliable. A further advantage is that the spring 67 greatly reduces the normal wear that takes place on the pivot wear points of the toggle joint.

The drive means 43 further includes a hydraulic cylinder 70 that is pivotally mounted on a bracket 68 mounted on a cross bar 69 that is bolted to the cross channels 23. The cylinder extends in a generally upward direction and has a piston rod 72 which is pivotally connected to the knee pin 51. The cylinder 70 is capable of moving the knee of the toggle joint from an acutely bent position illustrated in H6. 7, in which the gripping element 26 is inoperative, to a gripping position in which the toggle joint 44 is first below a straight line between the pivot pins 48 and 50, as shown in FIG. 2, to pivot the arm 27 to the operative position to grip a carbon anode. When the piston rod is in a fully retracted position, the knee of the toggle joint has been moved to a substantial over center position locking the toggle joint. This particular feature is more precisely illustrated in FIG. 6 showing the piston rod fully retracted with the knee of the toggle joint bearing against the end of the cylinder. This provides a locking mechanism to prevent the gripping element 26 from releasing the carbon anode should the cylinder 70 fail or the hydraulic pressure decrease substantially. If the power should be removed from the stacker, the gripping element will still grip the carbon block. The compression spring 67 enables the toggle joint 44 to move to the substantially straightened overcenter position without excessively wearing or subjecting the gripping element to excessive stresses.

The simplicity and effectiveness of the improved drive means 43 enables the gripping elements to be constructed at a minimum cost while providing unusual reliability in comparison to the prior art devices.

Having now described a preferred embodiment of my invention, I proceed to define my invention as follows.

lclaim:

1. In a carbon anode stacker for picking up a plurality of carbon anodes, conveying the anodes to a desired location and stacking the anodes at the location, said stacker having a plurality of gripping elements mounted on a common frame for individually gripping and releasing associated anodes, in which the gripping element has a pivot arm pivotally mounted on the frame with the improvement comprising a reversible drive means operatively connected to the pivot arm to grip and release the anode, said reversible drive means comprising:

a. a toggle joint operatively interconnected between the pivot arm and the frame having links pivotally interconnected at a knee to pivot the arm to grip the anode when the knee is straightened and to release the anode when the knee is substantially bent;

b. an actuator mounted on the frame operatively connected to the toggle knee for bending and straightening the knee; and

c. wherein one of the links has a variable length with a compression spring mounted thereon for extending said one link. 2. In a carbon anode stacker as defined in claim 1 wherein the variable length link has two telescoping members with the compression spring mounted thereon to bias the telescoping members outward to a predetermined length.

3. In a carton anode stacker for picking up a plurality of carbon anodes, conveying the anodes to a desired location and stacking the anodes at the location, said stacker having a plurality of gripping elements mounted on a common frame for individually gripping and releasing associated anodes, in which the gripping element has a pivot arm pivotally mounted on the frame with the improvement comprising a reversible drive means operatively connected to the pivot arm for pivoting the arm to grip and release the anode, said reversible drive means comprising:

a. a toggle joint operatively interconnected between the pivot arm and the frame having links pivotally interconnected at a knee to pivot the arm to grip the anode when the knee is straightened and to release the anode when the knee is substantially bent; an actuator mounted on the frame operatively connected to the toggle knee for bending and straightening the knee; c. wherein one of the links has a variable length with a compression spring mounted thereon for extending said one link; and wherein the actuator is a fluid operated cylinder having a piston rod connected to the toggle knee for moving the knee slightly past center to lock the knee in the substantially straightened position to maintain the grip on the anode even though the cylinder should become inoperative.

4. In a carbon anode stacker as defined in claim 3 wherein the cylinder is mounted on the frame opposing the toggle knee with the piston rod connected to the toggle knee to bend the toggle knee when the piston rod is extended and to straighten the knee slightly past center when the piston rod is in the fully retracted position. 

2. In a carbon anode stacker as defined in claim 1 wherein the variable length link has two telescoping members with the compression spring mounted thereon to bias the telescoping members outward to a predetermined length.
 3. In a carton anode stacker for picking up a plurality of carbon anodes, conveying the anodes to a desired location and stacking the anodes at the location, said stacker having a plurality of gripping elements mounted on a common frame for individually gripping and releasing associated anodes, in which the gripping element has a pivot arm pivotally mounted on the frame with the improvement comprising a reversible drive means operatively connected to the pivot arm for pivoting the arm to grip and release the anode, said reversible drive means comprising: a. a toggle joint operatively interconnected between the pivot arm and the frame having links pivotally interconnected at a knee to pivot the arm to grip the anode when the knee is straightened and to release the anode when the knee is substantially bent; b. an actuator mounted on the frame operatively connected to the toggle knee for bending and straightening the knee; c. wherein one of the links has a variable length with a compression spring mounted thereon for extending said one link; and d. wherein the actuator is a fluid operated cylinder having a piston rod connected to the toggle knee for moving the knee slightly past center to lock the knee in the substantially straightened position to maintain the grip on the anode even though the cylinder should become inoperative.
 4. In a carbon anode stacker as defined in claim 3 wherein the cylinder is mounted on the frame opposing the toggle knee with the piston rod connected to the toggle knee to bend the toggle knee when the piston rod is extended and to straighten the knee slightly past center when the piston rod is in the fully retracted position. 